Structural and magnetic properties of Cr-substituted NiZnCo ferrite nanopowders

Cr-substituted NiZnCo ferrite nanopowders, Ni0.5−xZn0.5CrxCo0.1Fe1.9O4 (0≤x≤0.20), were synthesized by sol-gel auto-combustion method. The effect of Cr substitution on the structural and magnetic properties have been investigated. Differential thermal analysis-thermogravimetry (DTA-TG), X-ray diffraction (XRD), Fourier transform infrared spectro-scopy (FT-IR) and vibrating sample magnetometer (VSM) measurements were used to characterize chemical, structural and magnetic properties. The DTA-TG results indicate that there are three steps of combustion process. FT-IR spectra confirm the formation of spinel structure during the self-propagation combustion. XRD results indicate that the lattice parameter and the X-ray density decrease, and the average crystallite size increase with increasing Cr substitution. And Fe2O3 secondary impurity phase formed with excess Cr substitution. The saturation magnetization increases with the increase of Cr substitution when x≤0.05, and decreased when x>0.05. Meanwhile, the coercivity monotonically decreases with the increase of Cr substitution.